This invention relates to coupler devices for releasably connecting a boom arm, such as that found on a power excavator or backhoe to a tool, such as a material handling bucket, and combinations incorporating such coupler devices.
It is known to provide excavators, power shovels and backhoes with different sizes and types of material handling implements, such as buckets to allow various operations. Known types of material handling tools, in addition to buckets, include grapples, pulverizers, and stump harvesters. To explain further, in the case of commonly used buckets on backhoe machines, a large bucket may be required for mounting on a boom arm of the machine to carry out certain types of digging operations, while a smaller bucket may be more suitable for another digging job. It is desirable to be able to change from one bucket or implement to another relatively easily and quickly and in a safe manner and, for this reason, a variety of so called quick couplers have been developed and used to facilitate such changeovers. These coupling devices are generally releasably connected to the boom arm of a machine, such as a backhoe, by means of large connecting pins which form pivot axes. The coupler can include a coupling frame which is adapted for connection to the boom arm by means of the connecting pins. Often the coupling device includes a hydraulic cylinder actuator to facilitate the attachment between the coupler and the tool.
U.S. Pat. No. 6,499,904 issued to Nye Manufacturing Ltd. describes a quick coupler for an excavator which uses a hydraulically operated actuator. This coupler has a coupling frame for connection to the boom, this frame having wedge members provided on opposite, vertically extending sides thereof. These wedge members are adapted to engage in channels formed by connecting members mounted on the tool. This coupler has a locking mechanism for securing the wedge members in the channels. The locking mechanism is mounted on the coupling frame and includes the hydraulically operated actuator and two slidable locking bars movable by this actuator between locking and unlocked positions. In the locking position, the locking bars extend into co-operating openings provided on the tool and thereby prevent the coupler from detaching from the tool.
Recent U.S. Pat. No. 6,379,075 issued Apr. 30, 2002 to GH Hensley Industries, Inc. describes a quick coupler that can be used to removably attach an excavation bucket to an outer boom end. A top portion of the coupler is pinned to the outer boom end and it has a bottom portion with spaced apart recesses configured to releasably receive portions of stick and curl pins on the bucket. An arcuate latch hook is translationally drivable by a hydraulic cylinder assembly toward one of the implement pins to releasably lock it in its associated coupler recess. A redundant safety mechanism is incorporated into this coupler and acts to hold the latch hook in its locking position. This second safety mechanism includes hydraulic and mechanical locking mechanisms and a spring structure that resiliently biases the latch hook towards its locking position.
The aforementioned '075 patent is also able to indicate to an operator of the excavator that the latch hook is in the unlocked position by a visual feature. In particular rear end portions of spring guide members project rearwardly beyond a rear end plate of the coupler to visually alert the operator that the latch hook is in the unlocked position and these rear end portions can be painted a bright color such as red so that they can be readily seen.
There remains a need for an improved coupler device for releasably connecting a boom arm to a tool, this device having a coupling frame with wedge members on opposite sides thereof adapted to engage in respective channels formed by connecting members mounted on the tool. In particular there is a need for such a coupler device with a fluid actuated holding mechanism for securing the wedge members in the channels and also a locking mechanism for locking the wedge members in the channels.